Django: Strange error with connection between view, template and url - django

Question

I have two main usage and main model pages, in which products from a specific usage or model are listed.
I have the following views for these pages:
def get_common_queryset():
usage_queryset = Usage.objects.all()
sub_usage_queryset = SubUsage.objects.all()
main_model_queryset = MainModel.objects.all()
pump_type_queryset = PumpType.objects.all()
queryset_dictionary = {
"usage_queryset": usage_queryset,
"sub_usage_queryset": sub_usage_queryset,
"main_model_queryset": main_model_queryset,
"pump_type_queryset": pump_type_queryset,
}
return queryset_dictionary
def products_usage_main(request):
queryset_dictionary = get_common_queryset()
context = queryset_dictionary
return render(request, "products/products_usage_main.html", context)
def products_model_main(request):
queryset_dictionary = get_common_queryset()
context = queryset_dictionary
return render(request, "products/products_model_main.html", context)
Here we have a get_common_queryset() function, which you can read about the reason of it in this question. Then we have two simillar view functions, products_usage_main and product_model_main but with different templates.
In the urls.py I have following paths for these views:
urlpatterns = [
path("application/", products_usage_main, name="products_usage_main"),
path("model/", products_model_main, name="products_model_main"),
]
In which, again, we can see that the two paths are similar with just different views.
And finally I have two separate templates for these two views, which their code is not needed or related to the problem I'm facing.
THE PROBLEM:
In my products page sidebar, I have two main links referencing /products/application/ and /products/model/, and when I click on the /products/application/, everything works just fine; but when /products/model/ is clicked, I get the following error:
ValidationError at /products/model/
['“model” is not a valid UUID.']
And when I looked into the traceback error, It said that the problem raised from product_detail view and in line product = Product.objects.get(id=pk), which has NOTHING to do with these two pages and their views!
Below is my product_detail view:
def product_detail(request, pk):
product = Product.objects.get(id=pk)
head_flow_dataset = HeadFlowDataSet.objects.filter(
product=product
).order_by("flow")
context_of_view = {
"product": product,
"head_flow_dataset_x": [],
"head_flow_dataset_y": [],
}
for head_flow in head_flow_dataset:
context_of_view["head_flow_dataset_x"].append(head_flow.flow)
context_of_view["head_flow_dataset_y"].append(head_flow.head)
queryset_dictionary = get_common_queryset()
context = {
**context_of_view,
**queryset_dictionary,
}
return render(request, "products/product_detail.html", context)
Below I'm sending complete error traceback in case you need it:
Internal Server Error: /products/model/
Traceback (most recent call last):
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\fields\__init__.py", line 2649, in to_python
return uuid.UUID(**{input_form: value})
File "C:\Users\Vahid Moradi\AppData\Local\Programs\Python\Python310\lib\uuid.py", line 177, in __init__
raise ValueError('badly formed hexadecimal UUID string')
ValueError: badly formed hexadecimal UUID string
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\core\handlers\exception.py", line 55, in inner
response = get_response(request)
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\core\handlers\base.py", line 197, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\products\views.py", line 152, in product_detail
product = Product.objects.get(id=pk)
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\manager.py", line 85, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\query.py", line 636, in get
clone = self._chain() if self.query.combinator else self.filter(*args, **kwargs)
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\query.py", line 1420, in filter
return self._filter_or_exclude(False, args, kwargs)
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\query.py", line 1438, in _filter_or_exclude
clone._filter_or_exclude_inplace(negate, args, kwargs)
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\query.py", line 1445, in _filter_or_exclude_inplace
self._query.add_q(Q(*args, **kwargs))
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\sql\query.py", line 1532, in add_q
clause, _ = self._add_q(q_object, self.used_aliases)
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\sql\query.py", line 1562, in _add_q
child_clause, needed_inner = self.build_filter(
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\sql\query.py", line 1478, in build_filter
condition = self.build_lookup(lookups, col, value)
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\sql\query.py", line 1303, in build_lookup
lookup = lookup_class(lhs, rhs)
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\lookups.py", line 27, in __init__
self.rhs = self.get_prep_lookup()
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\lookups.py", line 341, in get_prep_lookup
return super().get_prep_lookup()
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\lookups.py", line 85, in get_prep_lookup
return self.lhs.output_field.get_prep_value(self.rhs)
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\fields\__init__.py", line 2633, in get_prep_value
return self.to_python(value)
File "D:\Projects\Navid Motor\Website\Django\NavidMotor.com\.venv\lib\site-packages\django\db\models\fields\__init__.py", line 2651, in to_python
raise exceptions.ValidationError(
django.core.exceptions.ValidationError: ['“model” is not a valid UUID.']
[12/Dec/2022 11:22:53] "GET /products/model/ HTTP/1.1" 500 145337

Answer 1

Inorder to solve this problem, I reviewed my other views, specially the product_detail view, and I tried to understand why this view should be the source of this problem.
In my products/urls.py I had a path to product_detail view, which was as below:
path("<str:pk>/", product_detail, name="product_detail"),
On the other hand model page url, as mentioned above, was as below:
path("model/", products_model_main, name="products_model_main"),
So I guess that the simillarities between these two paths was the source of the problem, and when I changed path url of product_detal to path("product-detail/<str:pk>/, both pages worked just fine.
UPDATE:
I found another solution and the main reason for this problem. After changing the product_detail path as mentioned above, it got me thinking about the reason for this problem, because, other than products/model/ I had another url with this structure, products/application/; so, why this problem only occured on model page? Then I checked my urls.py file throughly, and this was full paths in products.urls:
path("application/", products_usage_main, name="products_usage_main"),
path("<str:pk>/", product_detail, name="product_detail"),
path(
"application/single-application/<str:pk>",
products_single_usage_list,
name="products_single_usage_list",
),
path("model/", products_model_main, name="products_model_main"),
path(
"application/single-application/sub-application/<str:pk>",
products_sub_usage_list,
name="products_sub_usage_list",
),
path(
"model/single-model/<str:pk>",
products_single_model_list,
name="products_single_model_list",
),
path(
"model/single-model/pump-type/<str:pk>",
products_single_type_list,
name="products_single_type_list",
),
]
As you can see the order of the urls, first url is products/application/ and the second one is products/<str:pk>; I think Django checks the urls in this order, and it expects the model in products/model/ to be the <str:pk> part in the second url. So, I changed the order of urls, and it just worked fine without any need to change the product_detail page url.
Final urls.py code:
urlpatterns = [
path("application/", products_usage_main, name="products_usage_main"),
path("model/", products_model_main, name="products_model_main"),
path("<str:pk>/", product_detail, name="product_detail"),
path(
"application/single-application/<str:pk>",
products_single_usage_list,
name="products_single_usage_list",
),
path(
"application/single-application/sub-application/<str:pk>",
products_sub_usage_list,
name="products_sub_usage_list",
),
path(
"model/single-model/<str:pk>",
products_single_model_list,
name="products_single_model_list",
),
path(
"model/single-model/pump-type/<str:pk>",
products_single_type_list,
name="products_single_type_list",
),
]
I hope this answer would be helpfull for others who might encounter a problem like this.